Many different types of rear loading refuse vehicles have been suggested and several different general types of mechanisms for actuating their packer blades in order to move refuse from the hopper-like bottoms of their tail gates into their bodies, have been disclosed in the patented art.
For examples, in each of the U.S. Pat. Nos. to Appleman et al 3,615,028 and Anderson 3,615,029 the tail gate has upwardly and forwardly inclined, linear guide tracks in its sidewalls and a transversely extending, massive carrier plate which slides in the guide tracks. The packer blade is pivotally mounted along its upper edge to the rear or lower edge of the carrier plate. The carrier plate also carries hydraulic cylinders which may be called "sweep cylinders" and which have pistons that are connected to the packer blade in order to swing it angularly relative to the carrier plate for sweeping the packer blade down into the refuse in the collecting hopper. The carrier plate is reciprocated in the guide tracks by hydraulic cylinders and pistons which are mounted on the exteriors of the sidewalls of the tail gate and are actuated to move the carrier plate and the packer blade upwardly and forwardly to move the refuse out of the tail gate into the refuse truck body. The base parts of the cylinders are positioned at the lower rear ends of the guide tracks and their piston rods extend upwardly and are connected to the carrier plate. The rods are extended to move the refuse out of the tail gate into the body and may be called "packing cylinders".
Arrangements like these have several problems including the fact that the carrier plate must be heavy enough to transport the hydraulic cylinders which sweep the packer blade down into the refuse receiving hopper at the rear of the tail gate, that movement being strongly resisted by the refuse in the hopper. In addition, the external cylinders are so located that the travel of the carrier plate and the packer blade downwardly and rearwardly is limited by the fact that the bodies of the cylinders are at the lower rear of the tail gate so that the outer ends of their piston rods can retract only to the upper ends of the cylinders. This also results in reduced ground clearance to achieve the same packer blade travel in the guide tracks and the same hopper capacity.
In addition, after the sweep cylinders have swung the packer blade down into the hopper, the assembly comprising the carrier plate and the packer blade becomes a rigid structure which must be pushed upwardly by the packing cylinders. At this point, the load of the refuse in the hopper which resists the packing movement is applied to the packer blade and the force applied by the packing cylinders to the carrier plate results in very heavy "up-truck" loading. If the packing cylinders are not aligned with the carrier plate guide tracks but are spaced above them, as in Anderson U.S. Pat. No. 3,615,029, the lever arm for the force of the packing cylinders is even greater. As a result, the guide tracks in such an arrangement must be very strong and much of the power of the packing cylinders is wasted.
A structure of the type shown in U.S. Pat. Nos. 3,746,192 and 3,777,917 both to Herpich et al, overcomes some of these difficulties by connecting the sweep cylinders between the upper rear portions of the tail gate and the packer blade itself. This eliminates the necessity for a carrier plate. The packer blade in such a construction is pivotally carried by slide blocks which travel in the inclined tracks. However, even though the construction of these patents eliminates the heavy carrier plate, the external, linearly acting hydraulic cylinders and rods still are limited by the location of the cylinders at the lower parts of the tracks. The geometry results in putting a heavy "down-load" on the tracks themselves when the packing cylinders are energized to move the packer blades for pushing a load of refuse upwardly and forwardly out of the hopper and into the refuse truck body. Again, the tracks must be very strong and some of the power of the packing cylinders is wasted.
It is, therefore, the principal object of the instant invention to provide a packer blade actuating mechanism for a tail gate for a rear loading truck that is not limited to the extent to which such mechanisms are limited in the constructions of the prior art discussed above.
Yet another object of the instant invention is to provide a mechanism for actuating the packer blade of a rear loading refuse vehicle which, by reason of its geometry, introduces balancing forces acting both toward the upper and lower sides of the guide tracks, partially offsetting each other and resulting in a net lower track loading, even though the cylinders exert force equal to that exerted by the cylinders of the above described prior art arrangements.
It is yet another object of the instant invention to provide a mechanism for the actuation of a packer blade in the tail gate of a rear loading refuse vehicle having linearly extending, upwardly and forwardly inclined guide tracks to guide the travel of the packer blade, so constructed and arranged that the guide tracks open toward the inner sides of the tail gate, the packing cylinders are located interiorly of the tail gate, their inclination relative to the guide tracks may be selected to accomplish substantial reduction in the track loading forces involved and greater ground clearance may be achieved while providing a loading hopper of a capacity comparable to that of prior art constructions or greater.
Yet another object of the instant invention is to provide a mechanism for cycling a packer blade through the tailgate of a rear loading refuse vehicle which reduces wear and destructive forces on the tailgate structure itself by transferring part of the forces to the vehicle body so that the tailgate structure may be constructed from less massive materials, reducing its cost and its dead weight.